The helicopter struck the ground in an almost-inverted, nose-down attitude, with considerable engine power being produced. Nothing was found to indicate that any airframe or system malfunction led to the loss of control. The circumstances of the accident are consistent with previous occurrences in which aircraft control was lost because of pilot incapacitation. The autopsy results indicated advanced coronary artery blockage, with the possibility of myocardial ischemia. However, it is not possible to conclude that incapacitation was a factor in the accident. Although the pilot's training program was sanctioned by the Rotorway factory, it was not strictly in accordance with the CARs. Because of recency requirements, the pilot's licence was not valid, and the pilot was not being properly supervised during solo flights. Supervision is required for safety and by regulations. However, compliance with the recency requirements and supervision by an instructor probably would not have affected the outcome of this occurrence. The wreckage was not found for two days despite an intensive search. Possible reasons for this difficulty include the following: the pilot did not file a flight plan or leave a flight itinerary, he was not supervised by an instructor, no one had observed his departure, and the aircraft did not have an emergency locator transmitter.Analysis The helicopter struck the ground in an almost-inverted, nose-down attitude, with considerable engine power being produced. Nothing was found to indicate that any airframe or system malfunction led to the loss of control. The circumstances of the accident are consistent with previous occurrences in which aircraft control was lost because of pilot incapacitation. The autopsy results indicated advanced coronary artery blockage, with the possibility of myocardial ischemia. However, it is not possible to conclude that incapacitation was a factor in the accident. Although the pilot's training program was sanctioned by the Rotorway factory, it was not strictly in accordance with the CARs. Because of recency requirements, the pilot's licence was not valid, and the pilot was not being properly supervised during solo flights. Supervision is required for safety and by regulations. However, compliance with the recency requirements and supervision by an instructor probably would not have affected the outcome of this occurrence. The wreckage was not found for two days despite an intensive search. Possible reasons for this difficulty include the following: the pilot did not file a flight plan or leave a flight itinerary, he was not supervised by an instructor, no one had observed his departure, and the aircraft did not have an emergency locator transmitter. The pilot lost control of the helicopter for undetermined reasons. The helicopter subsequently crashed.Findings as to Causes and Contributing Factors The pilot lost control of the helicopter for undetermined reasons. The helicopter subsequently crashed. The pilot did not conduct his solo training flights under the supervision of a flight instructor. The pilot had severe coronary artery disease, which might have resulted in myocardial ischemia before the loss of control. The emergency locator transmitter was not installed in the aircraft, which probably delayed the discovery of the wreckage.Other Findings The pilot did not conduct his solo training flights under the supervision of a flight instructor. The pilot had severe coronary artery disease, which might have resulted in myocardial ischemia before the loss of control. The emergency locator transmitter was not installed in the aircraft, which probably delayed the discovery of the wreckage.